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How long until someone is capable of making really big diamonds? I mean big like a soccer ball or something? Is it silly to wonder if we will one day be able

How long until someone is capable of making really big diamonds? I mean big like a soccer ball or something? Is it silly to wonder if we will one day be able to use diamond as a structural material?

lojack 10y ago
While diamonds are super hard, they'd make pretty poor structural materials. They don't stand up well to compressive forces, which is essential for buildings.
- jdmichal 10y ago
  They are very good at withstanding compressive forces, at least on small scales. It's shearing forces that I would be concerned with. https://en.wikipedia.org/wiki/Material_properties_of_diamond#Pressure_resistance https://en.wikipedia.org/wiki/Material_properties_of_diamond... https://en.wikipedia.org/wiki/Diamond_anvil_cell https://en.wikipedia.org/wiki/Diamond_anvil_cell
  - snovv_crash 10y ago
    The compressive strength can't be greater than sqrt(2)*shear, because at that point you get a diagonal shear. It might be a slightly different ratio if the material has different directional strengths, but the principle holds. At least, that's what I was taught in MechEng Materials.
    - jdmichal 10y ago
      Interesting. I know that as a crystal, diamond is going to have directional cleaving planes. Intuition says that that would be an issue with shearing loads, but at the same time it can obviously withstand very high pressures. I don't have any mech. background, so I appreciate your better informed viewpoint.
jdmichal 10y ago
Diamond isn't necessarily a good structural material. It has great hardness, but poor toughness. https://en.wikipedia.org/wiki/Material_properties_of_diamond#Toughness https://en.wikipedia.org/wiki/Material_properties_of_diamond...
HillaryBriss 10y ago
I think it would be pretty cool to see giant diamonds used in unexpected new applications in homes and buildings. > A diamond's exceptional properties (it is one of the hardest natural material on the planet, the most effective heat conductor, and largely unaffected by most acids) make it ideal for drilling, grinding, and cutting. I'd also like to see someone incorporate a layer of diamond into a CPU heat sink. Just because...
- vidarh 10y ago
  Imagine the pimped out gamer PC cases you'd get.
  - kbob 10y ago
    Sure. It's a great thermal conductor.
userbinator 10y ago
If they become really affordable, I'd love to have a giant, soccer-ball-sized diamond just for the fun of owning an enormous ultra-hard object that once used to be super-rare and expensive. The optical properties of a huge diamond would probably be quite interesting too.
- deleted 10y ago
  [deleted]
- spacemanmatt 10y ago
  Gallagher will drop one off a building for grins. I can't wait!
vlehto 10y ago
It's suprizingly poor for many things. We don't actually care about any single material property, we care about ratios. For structural component you want high tensile strenght, high stiffness, high toughness, low weight and low price. If you compare natural diamond to Eglin steel, diamond only wins in weight. Carbon fiber is better in every way, the only problem remaining how you glue the fibers together. One area of interest has been diamond like carbon for coatings of mechanical parts. (It's actually pitch black, don't get too exited. And it actually doesn't share the precise crystal structure either.) Again it has few very disfavorable characteristics. Typically good wear resistance comes from good H/E ratio. ( Hardness= hardness, E= Youngs modulus = stiffness ) Now diamond is too stiff. Glass and rubber have better ratios, and both are increasingly used as coatings while DLC seems to be stuck in a very small niche. Threatened by shitloads of different carbides and nitrides which often have better H/E, better strenght and better toughness, while being only slightly less hard. (Strenght and hardness are different things.) Also DLC dissolves into steel and burns in very hot temperatures. These are shared by actual diamonds. So diamond doesn't even cut it in hardcore cutting blades, where extreme hardness and compressive strenght would otherwise be useful. Only concrete and aluminum are routinely cut with diamond.
- shabble 10y ago
  This makes me wonder what the actual real-world equivalent of the SFF trope 'diamond edged monomolecular sword' might actually be, since it sounds like diamond would be a pretty poor material to actually use.
  - vlehto 10y ago
    I actually studied one mind-numbing material science book with medieval swords in mind to keep interest. Seems like the vikings got it right with high carbon steel. The only good improvement to it would be boride or hard chrome coating. But the main function of such would be temporary stop to corrosion. The major problem of swords is fatigue while notched. Low alloy steels are some of the best known materials for this. But they don't stay sharp very well and hardened high carbon steel can just cut through such beam. When you go from high carbon steel to very high carbon steel, you get additionally "left over austenite". A real time hardening method which helps both against nocthing and against fatigue. The stuff spontaneously quenches itself under stress(!). A reaction more commonly known to happen in manganese steel, but here it happens to lesser degree. https://en.wikipedia.org/wiki/Mangalloy https://en.wikipedia.org/wiki/Mangalloy
wycx 10y ago
Rather than single crystal diamond, nano-polycrystalline diamond[1](npd) is probably an all-round better structural material, as you don't have to worry about the cleavage planes of single crystals. Unfortunately, it can only be made at high pressure and temperature, and it requires significantly higher P (>20 GPa vs <10 GPa) and T than typical HPHT diamonds. That means (1) current HPHT apparatus cannot be used to make nano-polycrystalline diamond, and (2) it is unlikely that we will ever be able to make large single pieces, as large volumes at high pressure require very large presses. Synthetic industrial diamonds are typically made in China using hinge-type cubic anvil apparatus, whereas npd requires a Kawai-cell octahedral multi-anvil apparatus to reach higher pressure. Thus, the existing synthetic diamond infrastructre cant be used to make npd. The largest npd pieces reported in the literature are 15 x 15 mm cylinders, and they required a 6000 ton press. I don't want soccer-ball sized npd, just npd big enough, (as well as cheap and readily available) to make typically-sized anvils for high pressure apparatus. It is stronger than tungsten carbide, so it can go to higher pressures, and it is relatively transparent to x-rays, so it is easy to make in situ measurements. Widespread availability of such material would significantly change high pressure research. [1] http://www.grc.ehime-u.ac.jp/en/prius/facilities/himedia http://www.grc.ehime-u.ac.jp/en/prius/facilities/himedia

How long until someone is capable of making really big diamonds? I mean big like a soccer ball or something? Is it silly to wonder if we will one day be able to use diamond as a structural material?

lojack 10y ago

While diamonds are super hard, they'd make pretty poor structural materials. They don't stand up well to compressive forces, which is essential for buildings.

jdmichal 10y ago
They are very good at withstanding compressive forces, at least on small scales. It's shearing forces that I would be concerned with. https://en.wikipedia.org/wiki/Material_properties_of_diamond#Pressure_resistance https://en.wikipedia.org/wiki/Material_properties_of_diamond... https://en.wikipedia.org/wiki/Diamond_anvil_cell https://en.wikipedia.org/wiki/Diamond_anvil_cell
- snovv_crash 10y ago
  The compressive strength can't be greater than sqrt(2)*shear, because at that point you get a diagonal shear. It might be a slightly different ratio if the material has different directional strengths, but the principle holds. At least, that's what I was taught in MechEng Materials.
  - jdmichal 10y ago
    Interesting. I know that as a crystal, diamond is going to have directional cleaving planes. Intuition says that that would be an issue with shearing loads, but at the same time it can obviously withstand very high pressures. I don't have any mech. background, so I appreciate your better informed viewpoint.

jdmichal 10y ago

Diamond isn't necessarily a good structural material. It has great hardness, but poor toughness. https://en.wikipedia.org/wiki/Material_properties_of_diamond#Toughness https://en.wikipedia.org/wiki/Material_properties_of_diamond...

HillaryBriss 10y ago

I think it would be pretty cool to see giant diamonds used in unexpected new applications in homes and buildings. > A diamond's exceptional properties (it is one of the hardest natural material on the planet, the most effective heat conductor, and largely unaffected by most acids) make it ideal for drilling, grinding, and cutting. I'd also like to see someone incorporate a layer of diamond into a CPU heat sink. Just because...

vidarh 10y ago
Imagine the pimped out gamer PC cases you'd get.
- kbob 10y ago
  Sure. It's a great thermal conductor.

userbinator 10y ago

If they become really affordable, I'd love to have a giant, soccer-ball-sized diamond just for the fun of owning an enormous ultra-hard object that once used to be super-rare and expensive. The optical properties of a huge diamond would probably be quite interesting too.

deleted 10y ago
[deleted]
spacemanmatt 10y ago
Gallagher will drop one off a building for grins. I can't wait!

vlehto 10y ago

It's suprizingly poor for many things. We don't actually care about any single material property, we care about ratios. For structural component you want high tensile strenght, high stiffness, high toughness, low weight and low price. If you compare natural diamond to Eglin steel, diamond only wins in weight. Carbon fiber is better in every way, the only problem remaining how you glue the fibers together. One area of interest has been diamond like carbon for coatings of mechanical parts. (It's actually pitch black, don't get too exited. And it actually doesn't share the precise crystal structure either.) Again it has few very disfavorable characteristics. Typically good wear resistance comes from good H/E ratio. ( Hardness= hardness, E= Youngs modulus = stiffness ) Now diamond is too stiff. Glass and rubber have better ratios, and both are increasingly used as coatings while DLC seems to be stuck in a very small niche. Threatened by shitloads of different carbides and nitrides which often have better H/E, better strenght and better toughness, while being only slightly less hard. (Strenght and hardness are different things.) Also DLC dissolves into steel and burns in very hot temperatures. These are shared by actual diamonds. So diamond doesn't even cut it in hardcore cutting blades, where extreme hardness and compressive strenght would otherwise be useful. Only concrete and aluminum are routinely cut with diamond.

shabble 10y ago
This makes me wonder what the actual real-world equivalent of the SFF trope 'diamond edged monomolecular sword' might actually be, since it sounds like diamond would be a pretty poor material to actually use.
- vlehto 10y ago
  I actually studied one mind-numbing material science book with medieval swords in mind to keep interest. Seems like the vikings got it right with high carbon steel. The only good improvement to it would be boride or hard chrome coating. But the main function of such would be temporary stop to corrosion. The major problem of swords is fatigue while notched. Low alloy steels are some of the best known materials for this. But they don't stay sharp very well and hardened high carbon steel can just cut through such beam. When you go from high carbon steel to very high carbon steel, you get additionally "left over austenite". A real time hardening method which helps both against nocthing and against fatigue. The stuff spontaneously quenches itself under stress(!). A reaction more commonly known to happen in manganese steel, but here it happens to lesser degree. https://en.wikipedia.org/wiki/Mangalloy https://en.wikipedia.org/wiki/Mangalloy

wycx 10y ago

Rather than single crystal diamond, nano-polycrystalline diamond[1](npd) is probably an all-round better structural material, as you don't have to worry about the cleavage planes of single crystals. Unfortunately, it can only be made at high pressure and temperature, and it requires significantly higher P (>20 GPa vs <10 GPa) and T than typical HPHT diamonds. That means (1) current HPHT apparatus cannot be used to make nano-polycrystalline diamond, and (2) it is unlikely that we will ever be able to make large single pieces, as large volumes at high pressure require very large presses. Synthetic industrial diamonds are typically made in China using hinge-type cubic anvil apparatus, whereas npd requires a Kawai-cell octahedral multi-anvil apparatus to reach higher pressure. Thus, the existing synthetic diamond infrastructre cant be used to make npd. The largest npd pieces reported in the literature are 15 x 15 mm cylinders, and they required a 6000 ton press. I don't want soccer-ball sized npd, just npd big enough, (as well as cheap and readily available) to make typically-sized anvils for high pressure apparatus. It is stronger than tungsten carbide, so it can go to higher pressures, and it is relatively transparent to x-rays, so it is easy to make in situ measurements. Widespread availability of such material would significantly change high pressure research. [1] http://www.grc.ehime-u.ac.jp/en/prius/facilities/himedia http://www.grc.ehime-u.ac.jp/en/prius/facilities/himedia